How To Write a WordPress Plugin
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This document provides an overview of how to write a WordPress plugin in 3 steps: 1. Plugins add functionality to WordPress through hooks like actions and filters without modifying core code. Actions call functions when events occur, while filters modify values being returned. 2. Plugins include metadata like the name, description, and author to display in the admin interface. Code is hooked into WordPress using actions and filters. 3. More advanced plugins can use objects to organize code, support custom post types and settings, and be submitted to the official WordPress plugin directory. Careful coding and documentation is important to create high quality, well-supported plugins.
How To Write a WordPress Plugin
- 1. How to Write a WordPress Plugin Baltimore WordPress Meetup • September 19, 2011
- 2. What is a plugin? Written in PHP Adds functionality without affecting core code Plugin API
- 3. Hooks: Actions & Filters
- 4. Actions Hey, WP! I’d like to do this when you do that... Calls a function that performs an action, possibly with some data given by WP
- 5. Actions add_action( $hook_name, $function ); add_action(‘wp_head’, ‘my_custom_js’); add_action(‘wp_head’, array( $some_object, ‘my_custom_js_method’) ));
- 6. Actions init wp_head save_post
- 7. Filters Hey, WP! I’d like to change a value that you’re returning/ using... Calls a function that returns a final
- 8. Filters add_filter( $hook_name, $function ); add_filter(‘the_content’, ‘my_content_filter’); add_filter(‘the_content’, array( $some_object, ‘my_content_method) ));
- 9. Filters the_title the_content wp_email_from
- 10. Getting Started PHP file or folder containing PHP file Javascript, CSS, etc. /wp-content/
- 11. Plugin Information <?php /* Plugin Name: My Simple Plugin Plugin URI: http://theandystratton.com/my-plugin Description: Does something awesome. Version: 1.0 Author: theandystratton Author URI: http://theandystratton.com License: GPL2 */
- 12. Info Shows in Admin UI
- 13. Don’t Just Drop Code WordPress includes plugins while initializing Coding without hooking into actions/filters = explosion
- 14. Starting to Code What do you want to do? I want to add my personal signature to all posts.
- 15. Starting to Code What does my plugin do? Filter the content of all posts and append my signature.
- 16. Some Code Hey WP! When you’re processing standard content, call this function!
- 17. Take the value WP provides us, add my signature, give it back.
- 18. It’s as easy as that.
- 19. But we can complicate things...
- 20. Archives, Listings, etc. Oops. I mean, I only want it to add my signature to the single post, not listings/ archives.
- 21. Archives, Listings, etc. What do you want to do now? Filter the content of all posts and append my signature
- 22. IF we’re on a single post page, THEN add my signature.
- 23. But we can complicate things...
- 24. Post Type Content Oops. I have a custom post type called “Products,” and it’s adding my signature to those, too.
- 25. IF we’re on a single blog post page, THEN add my signature.
- 28. Using Objects Avoid tons of prefixed functions Use a prefixed class to hold all your actions/filters
- 29. Using Objects
- 30. Do All Kinds of Fun Stuff
- 31. Plugins Do Way More Custom Post Types Shortcodes Metaboxes and metadata management
- 32. Plugins Do Way More Settings Pages Settings Fields Incorporate Internationalization
- 33. Plugins Do Way More Redirect requests Modify Rewrite Rules Emulate CRON jobs (wp- cron.php)
- 34. Going Public
- 35. Get in the Repository Submit your plugin code http://wordpress.org/extend/plugins/ about/ http://wordpress.org/extend/plugins/ about/faq/
- 36. Get in the Repository Readme.txt http://wordpress.org/extend/plugins/ about/readme.txt
- 37. Get in the Repository Subversion access & management Support URL? Update within 2 years or hide
- 38. More Resources “Writing a Plugin” http://codex.wordpress.org/ Writing_a_Plugin “WordPress Coding Standards” http://codex.wordpress.org/ WordPress_Coding_Standards
- 40. Keep It Simple Stupid.
- 41. Code is poetry.
- 42. Thanks.